The invention relates to an apparatus for shaping thermoplastic materials or for laminating backing parts, comprising at least one locationally movable supporting device for a lower mould or a moulding receptacle and at least one locationally movable supporting device for an upper mould A preliminary blowing box which can be sealed off with respect to the atmosphere receives the supporting device with a lower mould or moulding receptacle during an operating procedure.
When moulding or laminating parts, in particular interior panelling parts for automobiles, two supporting devices for receiving a lower mould or a backing part are provided on a respective sliding table to achieve a rapid operating sequence, the sliding tables being able to enter alternately into a preliminary blowing box in a sealed form. In this case, the sliding tables are arranged at different heights, which inevitably leads to a certain limitation of the height of the moulded part or of the lower mould if the moulding station overall is to remain within reasonable outer dimensions. Furthermore, the sealable displaceability of the sliding tables at different heights is constructionally complex. A further major disadvantage exists when the upper mould is changed, since this mould has to be moved together with the necessary clamping framework downwards through the entire moulding station, which is laborious because of the confined space and great weight.
The object of the invention is to design an apparatus of the type explained at the beginning in such a way that, while the apparatus can be easily operated, short cycle times are possible and rapid mould changing is possible with a virtually unlimited height of the moulded part.
This object is achieved by providing a turntable for transporting the at least one supporting device, which turntable has for each supporting device a receiving place which is separated from the respectively neighbouring receiving place by a separating wall which closes an opening in the preliminary blowing box, apart from a small gap. When a supporting device is located underneath an upper mould in a working station provided in the preliminary blowing box, the small gap between the separating wall and the wall of the preliminary blowing box can be sealed off by a seal.
A major advantage of this design according to the invention is that, after a mould or a backing part has entered the preliminary blowing box, the latter is sealed by the separating wall and the associated seal in a very short time after the mould or backing part has reached the working position the preliminary blowing box, is therefore ready for use, and the receiving place remaining outside the preliminary blowing box can be immediately loaded with a new backing part. In comparison with an apparatus with a sliding table, this has the advantage that, with the same cycle time, that time which remains for loading the backing part is significantly longer since with the arrangement of sliding tables it is necessary to bring corresponding closing flaps into the closed position in order to seal off the preliminary blowing box. During this time, for safety reasons the operator cannot reach the receiving space to be newly loaded.
Another advantage is that all the receiving places remain at the same height, to be specific in the plane of the turntable, whereas in the case of an apparatus with multilevel sliding tables the working height changes in each case. Furthermore, there is virtually no restriction with regard to the height of the moulded part, which is the case in the design with sliding tables, since there the distance between the two sliding tables cannot be chosen to be of any desired size, which inevitably leads to a restriction on the height of the moulded part. The main element of the invention in this respect is the arrangement of a separating wall in connection with a seal, which separates a receiving place from neighbouring receiving places, the separating wall closing the through-opening for a lower mould or a backing part in the preliminary blowing box, so that both a negative pressure and a positive pressure can be built up in the preliminary blowing box according to the intended mode of operation. The expression supporting device is intended to mean, for example, a base plate for a mould or a backing part.
The seal is preferably arranged on the fixed wall of the preliminary blowing box and is able to be pressed against the separating wall.
The seal may, however, also be arranged on the separating wall and be able to be pressed against the fixed wall of the preliminary blowing box.
A particularly preferred design of the invention consists in that the seal is preferably formed as a flexible seal and is arranged in a groove of the wall of the preliminary blowing box along the rim of the opening and can be pressed against the separating wall by a pressure medium. The arrangement of the seal in the fixed wall of the preliminary blowing box has the advantage of the fixed arrangement of feed lines for the pressure medium to allow the seal to be pressed against the separating wall. If the seal is of a sufficiently flexible design, it retracts into the initial state of its own accord on account of the elasticity, so that the seal is not subjected to any frictional effect during the rotation of the turntable.
To intensify the effect of the retraction of the seal for the rotating operation of the turntable, it may be advantageous if the seal is subjected to a restoring force after the pressure medium is switched off. This can be produced for example by subjecting the seal to negative pressure. For example, the base of the groove in which a flexible seal is guided can be connected to a negative pressure source, whereby the seal is retracted into the groove and comes free from the separating wall more intensely and more quickly, whereby it is does not hinder the rotating operation and is also not subjected to any wear caused by the rotation of the turntable. The rapid retraction of the seal allows the rotating operation to commence earlier, which brings about a shorter cycle time.
A particularly simple design is obtained if the seal is formed as a tubular seal and the interior of the tube is able to be connected to a pressure source and/or a negative pressure source.
A constructionally simple design of the turntable and its sealing is obtained in an advantageous way by the turntable having on the underside a rotary bearing and a rotary drive, by the wall of the preliminary blowing box facing the rotary bearing being formed around the rotary bearing and the rotary drive with an indentation and by the separating wall having in the region of the indentation on both its sides a flange which covers this indentation and interacts with the seal arranged on the wall of the preliminary blowing box. This makes it possible to arrange an uninterrupted, continuous seal in the wall of the preliminary blowing box, which is not only constructionally simpler but also operationally more reliable.
To be able to change a mould, whether in the case of the turntable or in the case of the upper table, in a simple way, the turntable has at each receiving place two rests, which serve for receiving a supporting device for a lower mould or a backing part and can be transferred from a holding position for the supporting device into a letting-through position, in which a mould can be changed by lowering of the supporting device. With the aid of an additional lifting table, not only the lower mould but also subsequently the upper mould, lowered onto the rests, can be fetched in the working position of the turntable in the working station, and consequently a complete mould change can be carried out together with a clamping framework change.
Above the turntable, any arrangements of the upper moulds may be provided. For example, an upper mould may be arranged on an upper lifting table arranged above the turntable. This concerns the arrangement of a single upper mould, which interacts for example alternately with two lower moulds arranged on the turntable.
When a plurality of upper moulds are used, they may be respectively assigned to a sliding table which is vertically movable.
An advantageous combination with the design of the turntable and its possibilities for the arrangement of various lower moulds consists in that upper moulds are arranged on a mould receptacle which is mounted to be rotated and driven. In this case, the mould receptacle may be vertically movable.